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I'm building a Websocket server application in python 3. I'm using this implementation: https://websockets.readthedocs.io/
Basically I want to manage multiple client. Also I want to send data from 2 different thread (one for GPS + one for IMU) GPS thread is refreshed 1Hz, while IMU thread is refresh at 25Hz
My problem is in MSGWorker.sendData method: as soon as I uncomment the line @asyncio.coroutine and yield from websocket.send('{"GPS": "%s"}' % data) the whole method does nothing (no print("Send data: foo") in terminal)
However with these two line commented my code works as I expect except that I send nothing through the websocket.
But, of course, my goal is to send data through the websocket, I just don't understand why it doesn't work ? Any idea ?
server.py
#!/usr/bin/env python3
import signal, sys
sys.path.append('.')
import time
import websockets
import asyncio
import threading
connected = set()
stopFlag = False
class GPSWorker (threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
self.data = 0
self.lastData = 0
self.inc = 0
# Simulate GPS data
def run(self):
while not stopFlag:
self.data = self.inc
self.inc += 1
time.sleep(1)
def get(self):
if self.lastData is not self.data:
self.lastData = self.data
return self.data
class IMUWorker (threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
self.data = 0
self.lastData = 0
self.inc = 0
# Simulate IMU data
def run(self):
while not stopFlag:
self.data = self.inc
self.inc += 1
time.sleep(0.04)
def get(self):
if self.lastData is not self.data:
self.lastData = self.data
return self.data
class MSGWorker (threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
def run(self):
while not stopFlag:
data = gpsWorker.get()
if data:
self.sendData('{"GPS": "%s"}' % data)
data = imuWorker.get()
if data:
self.sendData('{"IMU": "%s"}' % data)
time.sleep(0.04)
#@asyncio.coroutine
def sendData(self, data):
for websocket in connected.copy():
print("Sending data: %s" % data)
#yield from websocket.send('{"GPS": "%s"}' % data)
@asyncio.coroutine
def handler(websocket, path):
global connected
connected.add(websocket)
#TODO: handle client disconnection
# i.e connected.remove(websocket)
if __name__ == "__main__":
print('aeroPi server')
gpsWorker = GPSWorker()
imuWorker = IMUWorker()
msgWorker = MSGWorker()
try:
gpsWorker.start()
imuWorker.start()
msgWorker.start()
start_server = websockets.serve(handler, 'localhost', 7700)
loop = asyncio.get_event_loop()
loop.run_until_complete(start_server)
loop.run_forever()
except KeyboardInterrupt:
stopFlag = True
loop.close()
print("Exiting program...")
client.html
<!doctype html>
<html>
<head>
<meta charset="UTF-8" />
</head>
<body>
</body>
</html>
<script type="text/javascript">
var ws = new WebSocket("ws://localhost:7700", 'json');
ws.onmessage = function (e) {
var data = JSON.parse(e.data);
console.log(data);
};
</script>
Thanks you for your help
582
Finally I got it ! It required Python 3.5.1 (while my distro provide only 3.4.3) and some help from Aymeric, the author of the websockets library (thanks to him).
#!/usr/bin/env python3
import signal, sys
sys.path.append('.')
import time
import websockets
import asyncio
import threading
stopFlag = False
class GPSWorker (threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
self.data = 0
self.lastData = 0
self.inc = 0
# Simulate GPS data
def run(self):
while not stopFlag:
self.data = self.inc
self.inc += 1
time.sleep(1)
def get(self):
if self.lastData is not self.data:
self.lastData = self.data
return self.data
class IMUWorker (threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
self.data = 0
self.lastData = 0
self.inc = 0
# Simulate IMU data
def run(self):
while not stopFlag:
self.data = self.inc
self.inc += 1
time.sleep(0.04)
def get(self):
if self.lastData is not self.data:
self.lastData = self.data
return self.data
class MSGWorker (threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
self.connected = set()
def run(self):
while not stopFlag:
data = gpsWorker.get()
if data:
self.sendData('{"GPS": "%s"}' % data)
data = imuWorker.get()
if data:
self.sendData('{"IMU": "%s"}' % data)
time.sleep(0.04)
async def handler(self, websocket, path):
self.connected.add(websocket)
try:
await websocket.recv()
except websockets.exceptions.ConnectionClosed:
pass
finally:
self.connected.remove(websocket)
def sendData(self, data):
for websocket in self.connected.copy():
print("Sending data: %s" % data)
coro = websocket.send(data)
future = asyncio.run_coroutine_threadsafe(coro, loop)
if __name__ == "__main__":
print('aeroPi server')
gpsWorker = GPSWorker()
imuWorker = IMUWorker()
msgWorker = MSGWorker()
try:
gpsWorker.start()
imuWorker.start()
msgWorker.start()
ws_server = websockets.serve(msgWorker.handler, '0.0.0.0', 7700)
loop = asyncio.get_event_loop()
loop.run_until_complete(ws_server)
loop.run_forever()
except KeyboardInterrupt:
stopFlag = True
#TODO: close ws server and loop correctely
print("Exiting program...")
Regards, Clément
110
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